Piston and skirt expanding ring therefor



July 26, 1932. H. F. PHILLIPS PISTON AND SKIRT EXPANDING RING THEREFOR Filed Feb. l0, 1932 Patented 26, I1932 mmoLn r.' Pampus, or BELMONT, mssacnusm'rs rrsiroN .aN-n sxinr nixrmnnrejame rnnnnrcn Application led February 10, 1932. Serial No. 592,009.

My invention has relation to improvements in iston and skirt expanding rings therefor and it consists lin the novel features of construction more fully set forth in the specification and pointed out in the claims.

`The present invention is an improvement over that shown in my Patent No. 1,806,416, dated Ma 19, 1931. and is directed tofeatures of t e expanding ring and means for 1securing said ring in the piston skirt that have been found desirable in practical operations. Y wardly bent terminals of the expanding rin which facilitate its insertion in and remova from the skirt of a piston. Another novel feature is the seating of the expanding ring in suitable recesses provided for this purpose in the piston skirt. The provision of special recesses to receive the expanding ring makes it possible to apply the expander to any type of piston regardless of its construction, as the recesses are specially provided to receive the expander and are located and shaped accordingly. These advantages, as well as others inherent inthe invention, will be better apparent from a detailed description thereof in connection with the accompanying drawing, in which:

Figure 1 is a side elevation of an aluminium or alloy piston with my improved skirt expander ring applied thereto; Fig. 2 is a horizontal cross-section through the piston skirt taken on the line 2-2 of Fig. 1; Fig. 3 is a perspective View of a piston rigidly held in a vise while a reaming tool is cutting one of the recesses on the inside of the skirt for receiving the expander.

Referring to the drawing, P represents an aluminium or alloy piston of a common construction having its skirt 1 provided with a horizontal slot 2 immediately below the bottom ring land 3, the skirt also being provided with an inclined longitudinally extending slot 4 extending from slot 2 to the bottom of the piston skirt. The slot 4 is approximately midway between the wrist pin bosses 5, 5 and,

as well understood, is provided for the purpose of allowing the skirt to contract circum- 3 ferentially to compensate for the expansion caused by the heat during operation. As

One of these new features is the in-l ponted out in the lpatent above referred to, aluminium or alloy pistons have little resilience and soon become permanently set so that subsequent wear results in a teetering action of the piston during reciprocation thereof.

In order to impart resilience to the piston skirt so that it will hug the cylinder wall under all operating conditions an expanding element in the shape of an open ring6 is inserted in the lower part of the skirt 1. In the princi al embodiment ofthe invention the ring 6 as inwardly turned terminal portions 7, 7 immediately adjacent to which are the piston expanding parts 8, 8 and opposite tov which is the piston expanding part 9. Between piston expanding parts 8, 8 and 9 are what may be termed ring-locking parts 10, 10, since'the parts 10, 10 are adapted to be seated in oppositely disposed recesses 11, 11 formed on the inside of skirt 1. A simple method of forming the recesses 11, 11 is shown in Fig. 3, wherein the piston P is secured by a clamp C in a block B securely held in a vise V while a special rotary-acting reaming tool T is applied to the inner wall of the piston skirt for cutting the recesses 11, 11. The recesses 11, 11 are slightly longer than the ring-locking parts 10, 10, and in order that the ring-locking parts 10, 10 mayv have free access into the recesses 11, 11 said ring-locking parts and the piston expanding parts 8 and 9 are separated by reentrant portions 12, 12 and 13, 13. In practice the ringlockingv parts 10, 10 and the piston expanding parts, 8, 8 and 9 are described by the same circle, the diameter of which is the same as that of the outside surfaceof the piston skirt before the expander 'Q is inserted therein. The expander must thus be contracted, preferably by applying a pair of pliers to the terminal portions 7 7 and u drawing the expander ends together', before it can be inserted into the pistonl skirt. On contracting the expander in this manner it may readily be placed within the skirt so that the ring-locking parts 10, 10 u will enter the recesses 11, 11 andthe ring-expanding parts 8, 8 and- 9 will exert tension outwardly on the piston skirt. There will be no tension exerted on the' piston skirt opposite the ring-locking parts 10, 10 as they will lo not bear against the piston 4wall on account of the recesses 11, 11. Thus, the skirt will be expanded across the diameter at right angles to the bosses 5, 5 to take up the wear on the 5 skirt wall as rapidly as it occurs. Obviously, there will be some expansion of the piston skirt in all directions, but the greatest amount of expansion Will be, as just stated, where it will be most effective to prevent the wear that results in a teetering of the piston in operation.

Having described my invention, I claim: 1. In combination with a piston having wrist pin bosses and a longitudinally slotted skirt provided with transverse grooves formed in the inner peripheral surface of said skirt below said bosses, an expanding element disposed within said skirt, parts of said element having Contact with and exerting ressure against said skirt and parts of sai element expanding into said grooves to decrease the pressure on the skirt at these points.

2. In combination with a piston having wrist pin bosses and a longitudinally slotted skirt provided with transverse grooves formed in the inner peripheral surface of said skirt below said bosses, an expanding element disposed within said skirt, parts of said element having contact with and exertin pressure against said skirt and parts of sai element expanding into said grooves to decrease the pressure on the skirt at these points, and tool receiving devices on the expanding element to facilitate handling the same. In testimony whereof I hereunto aiiix my signature.

HAROLD F. PHILLIPS. 

